1. Field of the Invention
The invention relates to a single short radiation pulse analyzer capable of measuring this radiation pulse. This pulse measurement may be applied to different types of radiation including X-ray or infrared radiation, visible radiation and electromagnetic energy.
The invention is applicable in all domains necessary for the measurement of a non-repetitive and very short radiation pulse, and particularly for the measurement of events generated by phenomena with a duration measured in picoseconds.
2. State of the Art
In general, pulse metrology is used to describe the variation with time of an electrical signal, and particularly its voltage or its energy when this signal is single (in other words not repetitive) and very short (in other words its duration is of the order of a few nanoseconds).
This type of signal to be measured is usually derived from very fast radiation detectors that convert energy from a radiation pulse that they received, into electrical signals. This type of radiation may be emitted by ultra-fast radiation sources such as lasers or synchrotronic radiation sources, or it may be the result of a radiation-material interaction, for example caused by an ultra-fast laser (in other words in which the pulse duration is of the order of a few picoseconds up to a few nanoseconds).
At the present time, instruments are available on the market for analyzing this type of single pulse signals (or electrical pulse) for which the spectrum range is up to 2 GHz. In particular, this type of instrument is marketed by INTERTECHNIQUE, TEKTRONIX(copyright), HP(copyright), LECROY(copyright), etc.
There are sampling oscilloscopes for measuring repetitive electrical pulses with a wider band, capable of measuring signals for which the spectrum range is up to 50 to 70 GHz.
The energies necessary to supply the radiation pulses are very high on some cases, and particularly during radiation-material type experiments. These experiments cannot be repeated; they are non-repetitive experiments.
At the present time, instruments are available for measuring single pulses, as described in U.S. Pat. No. 5,471,162. However, this electrical pulse measurement instrument must be associated with radiation detectors, before it can measure radiation pulses. This association is made using miscellaneous cables and connectors.
However, these detectors, cables, connectors and measuring instruments each have their own characteristics and pass bands, and their own impedances more or less well adapted to the assembly and their own rise time. Therefore the electrical signal is distorted by these successive transitions.
Furthermore, if the measurement instrument is based on the principle of spatial sampling, the electrical signal is distorted differently inside the instrument depending on the measurement point.
The purpose of the invention is to correct the disadvantages mentioned above.
Consequently, it proposes a single radiation pulse analyzer comprising radiation detectors that convert this radiation into an electrical signal, and means of measuring this signal by sampling at different times, without any spatial spreading of the signal.
More precisely, the invention relates to a single radiation pulse analyzer comprising:
a number of radiation detectors capable of receiving the radiation pulse and transforming it into a number of electrical signals;
a number of sampling means, each connected to one of the radiation detectors and capable of sampling the electrical signal output from the detectors at different times;
delay means, each connected to sampling means to delay the sampling time between two sampling means by a time interval (dt);
storage means, each associated with a sampling means to store information output from the said sampling means; and
means of reading and processing this information.
The electrical signals may be sampled at as many different times as there are sampling means.
Advantageously, the detectors are associated in the form of a network with two faces, polarized by a common electrode on one face and an individual central electrode on the other face.
According to one embodiment of the invention, the detectors form a square network addressed sequentially in rows and columns.
According to another embodiment of the invention, the detectors form a spiral network addressed starting from the center of the network.